A standard computer system typically includes integrated circuit devices mounted to a large printed circuit board known as a motherboard using a socket or similar type of electrical connector. The motherboard is supplied with voltage from a power supply, usually at a higher DC level than is required by the integrated circuit device.
Currently, a voltage regulator (i.e., a DC—DC converter) is used in certain high performance computer systems along with a pin grid array (PGA) socket. The central processing unit (CPU) package that connects to the socket consists of an integrated circuit device (e.g., a silicon chip) soldered to a package substrate using flipchip ball grid array (FCBGA) which, in turn, is soldered to one side of an interposer using ball grid array (BGA) technology. The package substrate connects to the PGA socket using multiple contacts in a matrix arrangement each having a pin type tail. The DC—DC converter connection consists of a multi-layer flex board and an edge-card connector that connects to one edge of the interposer substrate. The present configuration requires the CPU package to be inserted into the PGA socket in the vertical axis (i.e., the Z-axis). The DC—DC converter is then attached in the X-axis sliding direction requiring a complex retention mechanism.
In the recently developed land grid array (LGA) socket an array of pads, rather than pins, provide the requisite electrical connections between the integrated circuit device and the printed circuit board. LGA sockets are advantageous because they do not require soldering between the socket and the CPU package. Moreover, LGA sockets reduce the height of the socket/package/CPU solution (because they do not require the use of long pins) thereby resulting in shorter circuit paths and improved electrical performance. However, in order to connect the current DC—DC converter to an LGA socket, an interposer would be required to provide the edge-card interface required by the DC—DC converter. The interposer would add height, electrical path length, and parasitic inductance to the socket/package/CPU solution, thus negating the advantages of using the LGA socket.
Although multiple one ounce copper power planes may also be used to supply power from the DC—DC converter to the CPU socket through the motherboard, an excessive number of power and ground contacts would be needed and the additional power and ground planes make motherboard routing difficult. Delivering high DC currents through the motherboard to the LGA socket is an expensive solution and has additional technical challenges not associated with delivering current directly onto the LGA socket assembly.
Therefore, it would be advantageous to provide a low inductance and resistance interconnect that improves the current carrying capacity from the DC—DC converter to the LGA socket. It would also be helpful if the interconnect required only a single direction (vertical or Z-axis) of assembly which would save time and manufacturing costs.